The present invention relates to a polishing tool for polishing a coating surface into a predetermined shape.
There are various methods and kinds of polishing. A polishing work for a coating surface of a vehicle body such as an automotive vehicle, which requires a particularly high technique among those, will now be described.
In most general, the repair of the coating surface of a vehicle body such as an automotive vehicle is performed in accordance with the steps of peeling an old coating layer, feeding putty, grinding, masking, primary surface coating, cleaning and degreasing and surface coating as a final step in the stated order. In this surface coating step, after a final paint has been sprayed with a spray gun, xe2x80x9cgradationxe2x80x9d coating for eliminating a border between a portion on which the paint is coated and the portion on which no fresh paint is coated is performed, and finally, xe2x80x9ccoating polishingxe2x80x9d generally called polishing (hereinafter referred to as polishing) is performed.
The polishing work is a work for polishing and removing the uppermost layer portion of the coating layer by a polishing member coated with a polishing agent to obtain a condition where the thin oily layer is left on the coating surface (generally called a wet glossy condition). The polishing agent is generally called a compound (hereinafter referred to as compound) and is in general the material that is mixed with a synthetic resin, if necessary or for use, adding plasticizer, fillant, coloring agent, stabilizer, reinforcer and any other various ingredient and that may be used for molding in this condition. In the compound used in polishing an automotive vehicle or the like, particles of silicon oxide, fossil particles such as diatomaceous earth or particles of alumina or the like are mixed into a lubricant.
The work for polishing the coating surface smoothly with a manual polishing tool requires a rather large labor. Therefore, in order to reduce the labor, a mechanical polishing device (generally called a polisher and hereinafter referred to as a polisher) utilizing compressed air or electric power as a power source is used. This polisher is composed of a base member rotated and driven by a drive unit and having a mounting surface perpendicular to its rotary shaft and a polishing member mounted on the mounting surface for polishing the coating surface.
However, the polishing member used in this polishing tool suffers from a problem. In the polishing member designed for grinding rather than polishing (glossing), the polishing member per se is made relatively hard material or a polishing surface roughness of the polishing member is increased to enhance the cutting force. As a result, in any case, a remarkable damage or shade is left after polishing. Also, the polishing member designed for polishing (glossing) suffers a problem in that the polishing (grinding) force is deteriorated because the polishing member per se is made of relatively soft material or the coating surface roughness is made fine. A goodness of the polishing (grinding) characteristics depends upon the characteristics of roughness, hardness or the like of the particles of the compound so that the alliance with the polishing member is impossible and the polishing member is remarkably exhausted.
As shown in FIGS. 19, 20 and 21 as a polishing tool for solving this problem, it is therefore possible to propose a polishing tool 101 in which an elastic member 108 is interposed between a base member 106 and a polishing member 111. A plurality of holes 100 are provided along a circumferential edge of this elastic member 108. The polishing work for the coating surface is performed by a polisher 118 provided with this polishing tool 101.
Then, the plurality of holes 100 are provided in the elastic member 108 so that the pressure of ground contact with convex portions scattered on the coating surface when the polishing member 111 is brought into contact with the coating surface is increased. Namely, the contact area where the polishing member 111 is brought into contact with the coating surface is decreased but the pressure is concentrated on the arcuate portion forming the holes 100 to increase the pressure of ground contact. For this reason, it is possible to finish the coating surface in which both grinding and glossing functions are sufficiently exhibited.
Thus, it is possible to easily obtain the desired flat and finished polished surface without any high technical skill. In addition, the above-described theory in which the pressure of ground contact is increased, is a reasonable method for obtaining the flat polished surface. Accordingly, it is possible to obtain a desired polished surface for a necessary minimum period of time.
However, the holes 100 are provided on the circumferential edge of the elastic member 108 of the polishing tool 101 so that the ground contact area on the circumferential edge is considerably decreased in comparison with the ground contact area of the central portion. For this reason, there is nonuniformity in the coating surface. In order to avoid this, the operator must suitably operate the polishing tool 101 to the coating surface. Actually, a high technical skill is required for this.
Also, a centrifugal force is generated since the polishing tool 101 is operated at a high torque and at a high speed. Then, when the polishing tool 101 in operation is brought into contact with the static coating surface, the phenomenon called a bound in which the coating surface and the polishing tool 101 are repulsive to each other due to the centrifugal force is caused. This becomes a fatal damage in the polishing step that requires a uniform polishing work.
In view of the foregoing defects, an object of the present invention is therefore to provide a polishing tool with which a coating surface can be polished smoothly with an easy operation. Then, it is another object of the invention is to provide a polishing tool which can avoid a bound phenomenon. Also, it is still another object of the invention is to provide a polishing tool which can polish a coating surface smooth and glossy for a short period of time.
According to the present invention, a polishing tool includes a base member drivingly rotated by a drive unit and having a mounting surface perpendicular to its rotary axis, an elastic member to be mounted on the base member and a polishing member to be mounted on the elastic member, in which the elastic member has groove portions opened toward the polishing member side and extending from a center of the elastic member toward a direction of a circumferential edge thereof, and the opening edges of the grooves portions are linear from the center of the elastic member to the circumferential edge thereof.
Since the opening edges of the groove portions have linear portions, it is possible to perform polishing in a two-stage manner of linear portions and area portions. This means that first of all grinding (cutting) is effected with the linear portions to convex portions of the coating surface and thereafter glossing is effected with the area portions.
The polishing tool according to the present invention is composed of the above-described necessary elements but the invention may be established even if its structure may be the one described below in detail. The specific structural element is characterized in that the groove portions are provided to extend from the center to the circumferential edge of the elastic member. With this structure, the contact areas at the center and the circumferential edge are substantially the same each other to thereby make it possible to hardly create the non-uniformity in the polishing surface.
Incidentally, according to the present invention, it is preferable that the groove portions be radially provided from the center of the elastic member. With this structure, since the polishing member is uniformly bend along the grooves when the surface such as an edge portion, a corner portion or the like which has the concave and convex portions is to be polished, it is possible for the operator to easily perform the polishing work of the convex and concave surfaces without mastering a high technical skill like suitably adjusting the depression force every time.
Furthermore, the groove portions provided in the elastic member are formed so that their width is increased toward the circumferential edge. Moreover, the circumferential edge of the base member is formed to be movable. Accordingly, since the circumferential edge is well movable to the convex and concave portions, it is possible to polish more precisely an edge portion or a corner portion or the like that is difficult to be polished.
Also, the base member according to the present invention is characterized in that its elasticity is enhanced from the center toward the circumferential edge thereof. If the high elasticity is ensured in the circumferential edge of the base member, the movability of the circumferential edge is enhanced as described above and the polishing at the portion where the polishing has been difficult conventionally may readily be performed. According to this invention, in order to ensure the elasticity at the circumferential edge, the elastic material is used for the material of the surface plate portion and the thickness of the surface plate portion is defined so as to be decreased from the center to the circumferential edge thereof.
Furthermore, the polishing member is characterized in that it is formed of a material softer than that of the elastic member. Note that according to the present invention, it is preferable that the polishing member is made of soft sponge, wool or cloth material and the elastic member is made of hard elastic material.
Also, the polishing tool according to the present invention is characterized in that a shock moderating member is disposed between the base member and the elastic member. With this structure, the bound phenomenon that has been worried conventionally is absorbed by the shock moderating member so that the coating surface can be polished uniformly.
As described above, according to the present invention, it is possible to provide the polishing tool with which the coating surface can be polished smoothly with easy operation. Also, according to the present invention, the shock moderating member is clamped whereby it is possible to provide the polishing tool with which the bound phenomenon can be avoided. Also, the grinding (cutting) work is performed by line and the glossing work is performed by area, whereby it is possible to provide the polishing tool with which the coating surface can be polished smooth and glossy for a short period of time.